People are increasingly interacting with computers and other electronic devices in new and interesting ways. One such interaction approach involves making a detectable motion with respect to a device, which can be detected using a camera or other such element. While simple motions can be detected to provide input, there generally is no way to determine the identity of the person making the gesture, unless there is another process being used in combination such as facial recognition, which can be very resource intensive, particularly for mobile devices. If the motion is being made in contact with a display screen or other touch sensitive surface, a pattern such as a signature can be recognized to identify the person. In many cases, however, a person can learn to approximate another person's signature with enough accuracy to provide authentication. Further, a user might not appreciate having to continually be in contact with the device in order to provide for authentication of the user.